Speed control

I am refurbishing a Chinese Drill Press. One of the things that I am addressing is getting the speed down. Grizzly will sell me an intermediate pulley cheaply and I still need to design the mechanics for that.

However, this popped up and I wondered whether it might offer an alternative ?

I´ḿ no electrician. It does show it controlling some power tools. Any thoughts please ?

https://www.aliexpress.com/item/1005003327712897.html?ug_edm_item_id=1005003327712897&edm_click_module=item_detail&tracelog=rowan&rowan_id1=aeug_edm_24677_1_en_US_2022-04-11&rowan_msg_id=3249biz_pay_after_purchase:0:0_571530703$b0515c7c3927464796e37683b0ac382d&ck=in_edm_other

Cheers

Peter

Nooooo!!!!! Your drill press almost certainly uses a single speed induction motor and you can't change their speed with one of these crude SCR controllers.

Why not use simple pullies and belt, plus a low speed motor ?

If you want proper low speed grunt (torque) on a basic cheap machine then you must use pulleys or a backgear arrangement

Need to know the type of motor you have. As above, single phase induction motors are not good items to try it on (they are dependent, for speed, on frequency).

Yes, that was my first thought. Putting an extra pulley inside would make for very short belts, so I´m going to have to dispense with the casing and devise a way of mounting it externally and making a new belt guard.

Cheers

Peter

It´s an 850w single phase motor. There should be enough power.

Incidentally, the column is a mm under size. Perhaps I need to find a plater !

Cheers

Peter

NDIY means what sort of motor. I'd bet the farm on it being a single-phase induction motor with one or two capacitors like this example:

The capacitor is the white cylinder in the photo.

The speed controller you linked to is for a Universal Motor, which are often found on power-tools, and can vary their speed.

Machine tool motors are made differently and only runs at one speed, which is determined by your local mains frequency, either 50 or 60Hz.

Although there's an electronic controller which might do what you want, they're not popular or cheap. The easiest way to speed control a machine tool is to fit a 3-phase motor and VFD, or - if you're more adventurous - a Chinese Industrial Sewing Machine motor. The motor is Brushless and driven by a special controller, usually provided with the motor.

For slowing down a drill, I think gearing down with a pulley or gearbox is a better bet. The advantage of slowing down mechanically is it increases torque (turning power).

Are you certain the drill needs to be slowed down? More often people want to speed them up! Slow speed and plenty of torque is wanted for driving big twist drills, ½" or larger. Small drills like to be spun fast, a ¹⁄₁₆" drill at 6500rpm or more, which most pillar drills can't do.

Dave

Thank you !

Incidentally, it is 1850w not 850w. It is 230v 50hz and has an 8uF capacitor. I´m assuming that it is an induction motor.

The current speeds are 580, 850, 1250, 1650 and 2650.

Anything tiny, needing faster speeds, I have a Proxxon and GHT UPT for.

I felt that 580 was too fast for drills above 5/8".

Ideally, I would have liked a s/h Boxford or similar drill stand, but they aren´t available down here and I´m regarding what I´ve got as machined castings ! I have an ARCOY cast base for it, a longer column and I can get the extra pulley and belts from Grizzly in Germany. Bearings I can get locally and will replace.

Thank you

Cheers

Peter

Chinese drill with an 1850 watt motor and that speed range ? Unusual ?

And yes,580 would be a bit fast for 5/8" or above, I would be thinking something around 300 max, or even less.

I have a cheap Aldi bench drill, 1/2 HP motor which has no problem handling 1/2" drills, anything bigger I use the floor standing drill, again 1/2 HP or the mill 1-5 HP.

Pullies would seem to be the way to go.

An induction motor, running on single phase , UK is likely to have a speed of about 1470 rpm if a four pole, or 2850 if a two pole unit.

Those numbers can be the starting point for your calculation to arrive at pulley sizes to deliver the spindle speeds that you want.

It is very likely that you will need to use a two stage reduction, so assuming that the present set up provides four speeds, four sheave pulleys pulley should provide you with 12 possible speeds. (Three sheave pulleys will provide 9 possible speeds )

The problem is going to be locating the shaft for the intermediate pulley.

To keep belt lengths as short as posible, it will probably mean mounting the internediate shaft and pulley to one side of the existing casing, with the attendant need to design suitable adjustment, and guards for the belts.

Howard

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If you change to Poly-V pulleys, you could easily get a slower set of speeds

[ they wrap successfully around small diameters ]

MichaelG.

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P.S. __ Just a wild guess, based on searching for your list of speeds …

Is it anything like this machine ?

https://static-content.cromwell.co.uk/pdfs/s/Packaging/Osaki/279/OSA-279-9340K_Instructions.pdf

Edited By Michael Gilligan on 14/04/2022 18:08:26

1850w is a very big motor - about 2.5hp, so it must be a pretty hefty drill-press. My Naerok drill-press is only .55Kw, which is more than powerful enough for me. However, I too wanted slower speeds than the belt drive allowed so I replaced the 1ph motor with a 3ph equivalent and fitted a VFD. I've now got variable speeds and instant reverse with the twist of a knob and touch of a switch.

thanks for the cool ideas!